\name{as.owin}
\alias{as.owin.ppm}
\alias{as.owin.kppm}
\alias{as.owin.dppm}
\alias{as.owin.msr}
\alias{as.owin.quadrattest}
\alias{as.owin.rmhmodel}
\title{Convert Data To Class owin}
\description{
Converts data specifying an observation window
in any of several formats, into an object of class \code{"owin"}.
}
\usage{


 \method{as.owin}{ppm}(W, \dots, from=c("points", "covariates"), fatal=TRUE)

 \method{as.owin}{kppm}(W, \dots, from=c("points", "covariates"), fatal=TRUE)

 \method{as.owin}{dppm}(W, \dots, from=c("points", "covariates"), fatal=TRUE)

 \method{as.owin}{msr}(W, \dots, fatal=TRUE)

 \method{as.owin}{quadrattest}(W, \dots, fatal=TRUE)

 \method{as.owin}{rmhmodel}(W, \dots, fatal=FALSE)



}
\arguments{
  \item{W}{
    Data specifying an observation window, in any of several formats
    described under \emph{Details} below.
  }
  \item{fatal}{
    Logical value determining what to do
    if the data cannot be converted to an observation window.
    See Details.
  }
  \item{\dots}{Ignored.}
  \item{from}{Character string. See Details.}
}
\value{
  An object of class \code{"owin"} (see \code{\link{owin.object}})
  specifying an observation window.
}
\details{
  The class \code{"owin"} is a way of specifying the observation window
  for a point pattern. See \code{\link{owin.object}} for an overview.
 
  The generic function \code{as.owin} converts data in any of several formats 
  into an object of class \code{"owin"} for use by the \pkg{spatstat}
  package. The function \code{as.owin} is generic, with methods
  for different classes of objects, and a default method.

  The argument \code{W} may be
  \itemize{
    \item
    an object of class \code{"owin"}
    \item
    a structure with entries \code{xrange}, \code{yrange} specifying the 
    \eqn{x} and \eqn{y} dimensions of a rectangle
    \item
    a structure with entries named \code{xmin}, \code{xmax}, \code{ymin},
    \code{ymax} (in any order) 
    specifying the \eqn{x} and \eqn{y} dimensions of a rectangle.
    This will accept objects of class \code{bbox} in the \code{sf} package.
    \item
    a numeric vector of length 4
    (interpreted as \code{(xmin, xmax, ymin, ymax)} in that order)
    specifying the \eqn{x} and \eqn{y} dimensions of a rectangle
    \item
    a structure with entries named \code{xl}, \code{xu}, \code{yl}, \code{yu}
    (in any order)
    specifying the \eqn{x} and \eqn{y} dimensions of a rectangle
    as \code{(xmin, xmax) = (xl, xu)} and 
    \code{(ymin, ymax) = (yl, yu)}. This will accept objects of
    class \code{spp} used in the Venables and Ripley \pkg{spatial}
    package.
    \item
    an object of class \code{"ppp"} representing a point pattern.
    In this case, the object's \code{window} structure will be
    extracted.
    \item
    an object of class \code{"psp"} representing a line segment pattern.
    In this case, the object's \code{window} structure will be
    extracted.
    \item
    an object of class \code{"tess"} representing a tessellation.
    In this case, the object's \code{window} structure will be
    extracted.
    \item
    an object of class \code{"quad"} representing a quadrature scheme.
    In this case, the window of the \code{data} component will be
    extracted.
    \item
    an object of class \code{"im"} representing a pixel image.
    In this case, a window of type \code{"mask"} will be returned,
    with the same pixel raster coordinates as the image.
    An image pixel value of \code{NA}, signifying that the pixel
    lies outside the window, is transformed into the logical value
    \code{FALSE}, which is the corresponding convention for window masks.
    \item
    an object of class \code{"ppm"}, \code{"kppm"} or \code{"dppm"}
    representing a fitted point process
    model. In this case, if \code{from="data"} (the default),
    \code{as.owin} extracts the  original point
    pattern data to which the model was fitted, and returns the
    observation window of this point pattern. If
    \code{from="covariates"} then \code{as.owin} extracts the
    covariate images to which the model was fitted,
    and returns a binary mask window that specifies the pixel locations.
    \item
    A \code{data.frame} with exactly three columns. Each row of the
    data frame corresponds to one pixel. Each row contains the
    \eqn{x} and \eqn{y} coordinates of a pixel, and a logical value
    indicating whether the pixel lies inside the window.   
    \item
    A \code{data.frame} with exactly two columns. Each row of the
    data frame contains the \eqn{x} and \eqn{y} coordinates of a pixel
    that lies inside the window.
    \item
    an object of class \code{"distfun"}, \code{"nnfun"}
    or \code{"funxy"} representing a function of spatial location,
    defined on a spatial domain. The spatial domain of the function will be
    extracted.
    \item
    an object of class \code{"rmhmodel"} representing a
    point process model that can be simulated using \code{\link{rmh}}.
    The window (spatial domain) of the model will be extracted.
    The window may be \code{NULL} in some circumstances (indicating that the
    simulation window has not yet been determined). This is not treated
    as an error, because the argument \code{fatal} defaults to
    \code{FALSE} for this method.
    \item
    an object of class \code{"layered"} representing a
    list of spatial objects. See \code{\link{layered}}.
    In this case, \code{as.owin} will be applied to each
    of the objects in the list, and the union of these windows
    will be returned.
    \item
    an object of class \code{"SpatialPolygon"},
    \code{"SpatialPolygons"} or \code{"SpatialPolygonsDataFrame"}.
    To handle these data types,
    \bold{the package} \pkg{maptools} \bold{must be loaded},
    because it provides the methods for \code{as.owin} for these classes.
    For full details, see \code{vignette('shapefiles')}.
  }
  If the argument \code{W} is not in one of these formats
  and cannot be converted to a window, then an error will
  be generated (if \code{fatal=TRUE}) or a value of \code{NULL}
  will be returned (if \code{fatal=FALSE}).

  When \code{W} is a data frame, the argument \code{step}
  can be used to specify the pixel grid spacing; otherwise, the spacing
  will be guessed from the data.
}
\seealso{
  \code{\link{owin.object}},
  \code{\link{owin}}.

  Additional methods for \code{as.owin} are provided
  in the \pkg{maptools} package:
  \code{as.owin.SpatialPolygon},
  \code{as.owin.SpatialPolygons},
  \code{as.owin.SpatialPolygonsDataFrame}.
}
\examples{
 w <- as.owin(c(0,1,0,1))
 w <- as.owin(list(xrange=c(0,5),yrange=c(0,10)))
 # point pattern
 data(demopat)
 w <- as.owin(demopat)
 # image
 Z <- as.im(function(x,y) { x + 3}, unit.square())
 w <- as.owin(Z)

}
\author{
  \spatstatAuthors.
}
\keyword{spatial}
\keyword{manip}
 
 
